[BUG] NO_PROXY stopped working in 2.1.23

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Starting in 2.1.23 and continuing through 2.1.29 my NO_PROXY settings are being ignored and the proxy is being used for my ANTHROPIC_BASE_URL.

{
"env": {
"CLAUDE_CODE_ENABLE_TELEMETRY": "0",
"ANTHROPIC_MODEL": "anthropic.claude-sonnet-4-5-20250929-v1:0",
"ANTHROPIC_BASE_URL": "https://my-litelllm-endpoint.example.com",
"DISABLE_AUTOUPDATER": "1",
"ANTHROPIC_AUTH_TOKEN": "litellm token",
"NO_PROXY": "127.0.0.1,.example.com",
"HTTPS_PROXY": "http://myproxy.somedomain.com:8080/",
"HTTP_PROXY": "http://myproxy.somedomain.com:8080/",
"DISABLE_INSTALLATION_CHECKS": "1"
}
}

With 2.1.22 and before traffic to my ANTHROPIC_BASE_URL would not pass through the proxy because I included .example.com in my NO_PROXY settings. Starting with 2.1.23, the proxy is used when trying to connect to my ANTHROPIC_BASE_URL .

What Should Happen?

Claude Code should not use the PROXY when the ANTHROPIC_BASE_URL's domain is in NO_PROXY.

Error Messages/Logs

I get errors from my proxy

Steps to Reproduce

With a LiteLLM endpoint setup your proxy and exclude that endpoint from your proxy via NO_PROXY. You will see that the proxy is being used for accessing the ANTHROPIC_BASE_URL

{
"env": {
"CLAUDE_CODE_ENABLE_TELEMETRY": "0",
"ANTHROPIC_MODEL": "anthropic.claude-sonnet-4-5-20250929-v1:0",
"ANTHROPIC_BASE_URL": "https://my-litelllm-endpoint.example.com",
"DISABLE_AUTOUPDATER": "1",
"ANTHROPIC_AUTH_TOKEN": "litellm token",
"NO_PROXY": "127.0.0.1,.example.com",
"HTTPS_PROXY": "http://myproxy.somedomain.com:8080/",
"HTTP_PROXY": "http://myproxy.somedomain.com:8080/",
"DISABLE_INSTALLATION_CHECKS": "1"
}
}

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.22

Claude Code Version

2.1.29 (Claude Code)

Platform

Other

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_